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Gravity systems



  • Karl_4
    Karl_4 Member Posts: 11

    My grandmother has a gravity system and is working fine. I've heard they are not very efficient to operate, is this true? Would it be beneficial to add a circulator to the system without changing the boiler? Money is an issue.
  • Al Letellier_9
    Al Letellier_9 Member Posts: 929
    gravity heating

    It depends.....a properly installed gravity system can be the most comfortable of all systems (short of radiant). The efficiency issue is that the old boiler were so big and inefficient by todays standards. If money is an issue and the old system is working fine, let it be until you can afford to do it right. Just adding a curculator won't necessarily save you any money, and the heat won't be as even. Consult a pro with a lot of experience with gravity heat before making the leap.

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  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    Very true Al

    I love the old gravity systems. When I do upgrade I put in the smallest circulator I can so the characteristics are not changed too drastically. Usually a Grundfos UPS 15-58 on it's lowest speed. There can be issues with possible orifices on the upstairs radiators used by the Deadman to slow convection so the upstairs didn't overheat. The radiators for gravity are oversized greatly as compared to modern day systems so it could generate enough heat at the low water flow it worked at. These big old cast iron beasties work very well with the modern condensing boilers since they don't need as high of water temperatures to heat with. I've been told the systems I upgraded have saved over 50% on past fuel bills because of the condensing technology used with old cast iron rads. I use 155 degrees on the coldest day on the reset curve and havent heard any complaints. WW

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  • Charlotte
    Charlotte Member Posts: 1
    Pressure increase - gravity system

    I recently added a new valve and thermocouple on a 70 year old gravity, closed tank, hot water system to bring it up to code. Now the pressure goes up to about 20 psi after it runs for awhile. It goes back down after being cold for a few hours. Is this a problem? Should I be concerned?
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